We are interested in determining basic principles of how the nervous system develops and some of the roles that genes play in producing normal neural development. Specifically, we are proposing a search for developmental similarities and differences in the neuronal connections forming early reflex pathways in the spinal cords of different inbred mouse strains. Our primary experimental approach is to determine whether there are strain differences in the development of reflex movements elicited by cutaneous stimulation. We then plan to attempt to define the morphological substrate underlying strain similarites and differences in reflex behavior using a range of neuroanatomical procedures including electron microscopy, autoradiography and classical neurohistological stains. When strains are found which exhibit marked variations in our "developmental phenotype" they will be crossed and F1, backcross and F2 generations will be examined behaviorally, as well as morphologically, to determine the mode of inheritance of the developmental trait. It is anticipated that studies in the field of our proposed research will contribute toward both an understanding of normal brain development and the neuroembryological processes regulated by genes. It is hoped that such knowledge will provide stepping-stones for investigations of cases where genetically-associated abnormalities of brain development are the suspected basis of adult brain disorders.